Blueprint, photo-vellum, and similar sensitized cloths



Patented June 21, 1938 UNITED. STATES SENSI TIZED CLOTHS BLUEPRIN T, PHOTO-VELLUM,

PATENT OFFICE ANDSIMIWLAR' Arnold Leroy Llppert and wima'm r. Hall, Wilj mington, Del., assignors to Joseph Bancroft & Sons (30., Wilmington, Del., a corporation of Delaware No Drawing.

such as kaolin, talc and barium sulphate, about 5% softener such as sulphonated tallow, ammonium' stearate, and paraflin, and about 5% titanium dioxide; or the usual variations thereof. The sized cloth is then sensitized, ferrocyanide being ordinarily employed.

One of the primary objects of the invention is to provide such a sized cloth, in which, however, the color is improved and in which the likelihood of bleeding of the exposed portions into the unexposed portions is substantially prevented,

giving sharpness of lines.

It is a further object to provide such a cloth in whichthe sizing does not bleed into the solutions and, therefore, the solutions do not build up in concentration of sizing, as is the case with the usual sized cloth employed for this purpose.

More particularly, it is an object of the invention to fix the sizing and to increase its water repellence, extending the useful life of the print.

We also propose a treatment for such blueprint cloth which will secure the above characteristics in a simple and economical manner.

In carrying out our invention, we proceed as follows. Sized cloth, preferably calendered to increase smoothness of surface, is treated with a solution of the resin, urea formaldehyde. This is a synthetic, water soluble, water white resin having, in the polymerized state, some capacity for absorbing moisture. -The solution is preferably prepared by dissolving the urea and the fo'rmaldehyde in water; and dissolving a basic or acid resin being from about 1% to about and de-' sirably 5%, of the weight of the total solution. One may go as high as 25%.

This solution is applied to the sized cloth inany known way, such, for example, as-a Scotch mangle or friction padder rolls, the lower one of which runs in the solution. The cloth may be run through twice to treat both faces, and the lower roll is preferably of relatively soft rather than hard rubber.

Application November 7, 1986, Serial No. 109,154 1 v By pre-calendering the sized cloth, less of the solution is required for a given coverage.

The treated cloth is now run over heating cans of a. temperature of about 200 F. for about 1 minute. The roll of cloth is' then allowed tocure for about 24 hours after which it is steamed and then calendered at about 250 F., with about four tons pressure, being run through once on each side. 4

The resin solution primarily fixes the starch which is the adhesive of ,the sizing. The heat sets or polymerizes the resin with the result that l The some moisture, it can be 'efiectively sensitized.

After the print is made from the cloth, it is subjected to an oxidizing medium, such as sodium dichromate in solution, and is washed and dried.

When a print made with such treated cloth is developed, the effect is to make the blue appear to be more deep in color. This is probably not actually the case. but it seems to occur. The treatment prevents the dispersion of the sizing so that, in the case of the treated cloth, less of the white appears in the blue and the blue, therefore, appears deeper in color, as contrasted with untreated sized cloth. Similarly, the fixing of the sizing prevents bleeding from the exposed areas into the unexposed areas, in consequence of which the lines appear much more sharp.

Likewise the fixingv of the sizing practically eliminates bleeding into the sensitizing and developing solutions and washes, so that they do not build up in concentration of sizing, as is the case with untreated sized cloth. The treated cloth is also superior in the other respects noted.

Photo-vellum is similarly treated.

We claim:

1. The process of treating sized cloth tobe sensitized which comprises subjecting the dry sized cloth to a solution of urea formaldehyde, polymerizing the resin, and sensitizing the treated cloth when dry.

sized cloth to a solution of urea formaldehyde, polymerizing the resin, and sensitizing the treated cloth when dry, the concentration of the resin 2. The process of treating sized cloth to be, sensitized which comprises subjecting the dry in the solution being substantially from 1% to about 10% of the total solution by weight.

3. The process of treating sized cloth to be sensitized which comprises subjecting the dry sized cloth to a solution oi! urea formaldehyde, subjecting the cloth to a temperature of about 200 F. for about one minute, allowing the treated cloth to cure for about 24 hours, calendering the cured cloth and sensitizing.

4. The process of treating sized cloth to be sensitized which comprises subjecting the dry sized cloth toa solution of urea formaldehyde, subjecting the cloth to a temperature of about 200 F. for about one minute, allowing the treated cloth to cure for about 24 hours, calendering the cured cloth and sensitizing, the cured cloth being steamed before calendering.

5. The process of treating sized cloth to be sensitized which comprises subjecting the dry sized cloth to a solution of urea formaldehyde, subjecting the cloth to a temperature or about 200 F. for about one minute, allowing the treated cloth to cure for about 24 hours and sensitizing, the cured cloth being steamed beiore calendering, the calendering being done at about 4 tons per sq. in. pressure.

' ARNOLD LEROY LIPPER'I. WILLIAM P. HALL. 

